The present invention relates to an automatic transmission for use in an automobile, and more particularly, to a transmission control system and method for controlling a transmission in the situation where a second transmission shift request occurs while a previous gear-shifting operation is still being performed.
In the typical prior art automatic transmission, if a new transmission shift request is input to a transmission control unit that is currently performing a prior gear-shifting operation, the transmission control unit triggers a gear-shifting operation of the newly requested transmission shift request immediately, regardless of whether the foregoing gear-shifting operation is completed.
Since the foregoing gear-shifting operation is abruptly stopped as soon as the new transmission shift request occurs, applying/releasing actions of hydraulic pressure of the foregoing gear-shifting operation are ceased in an unfinished state. In this situation, when the new gear-shifting operation for the new transmission shift request is immediately started, newly triggering application of the hydraulic pressure, there may be a shifting shock due to an interlock of the hydraulic pressure in some hydraulic ports or the like, degrading quality of the shifting operation of the transmission.
The present invention provides a transmission control system and method that is capable of preventing abnormal shifting shock from occurring when a new transmission shift request occurs while a prior gear-shifting operation is still being performed, and which is capable of completely performing the new gear-shifting operation of the new transmission shift request.
According to a preferred embodiment of the invention, the transmission control system comprises a shift lever whose position is changeable through a lever-shifting action by a driver selecting a transmission stage to be changed into; a transmission stage detection unit for detecting a new position of the shift lever due to the lever-shifting action, and outputting corresponding signals; and a transmission control unit receiving the signals from the transmission stage detection unit and performing a gear-shifting operation of the transmission. The transmission control unit contains a time map of a number of values of permissible time intervals that respectively correspond to all kinds of gear-shifting operations of the transmission. When a new transmission shift request is input to the transmission control unit while still performing the prior gear-shifting operation, the transmission control unit allows the currently performed prior gear-shifting operation to be held only during a corresponding permissible time interval set in the time map and then performs the newly requested gear-shifting operation.
In accordance with a preferred embodiment, the transmission control system further comprises a timer to monitor the time lapse relative to the permissible time interval and send signals corresponding to a current time to the transmission control unit. If the prior gear-shifting operation is completed before the permissible time interval is fully elapsed, the transmission control unit performs the new gear-shifting operation of the new transmission shift request immediately.
Further, the present invention provides a transmission control method comprising performing a first gear-shifting operation, determining whether a new transmission shift request exists while the first gear-shifting operation is being performed, obtaining a permissible time interval related to the first gear-shifting operation from a time map, if the new transmission shift request exists in the step (b), continuing to perform the first gear-shifting operation during the permissible time interval obtained from the time map, while delaying a new gear-shifting operation of the new transmission shift request, and performing the new gear-shifting operation after the permissible time interval has elapsed.